As known, any type of rolling bearing requires adequate lubrication during the operating conditions of its life cycle. Typically used are the kinds of grease based on mineral oil, thickened with lithium soap, which has good thermal stability, oxidation and mechanical properties as well as excellent water resistance and rust protection.
For example, in the case of bearings having a double row of rolling bodies, typically the grease is inserted in the central area comprised between the two rows. During the operating conditions of the bearing, the grease migrates between the various parts of the bearing in a completely random way, due to many factors, most of which are not controllable. The result is that often certain areas requiring a greater quantity lubrication receive few grease and tend to prematurely wear, while on the contrary the grease accumulates in areas requiring less lubrication causing unwanted friction losses.
Grease dispenser devices or lubricants cartridges are known. Purpose of said devices is to retain the grease, creating a sort of obstacle to its free outflow, and to provide the grease in a sufficiently controlled way during the working life of the bearing. For example in the document U.S. Pat. No. 5,803,616 a grease dispenser device is described, device which is mounted on the outer ring of the bearing, between the two rows of tapered rollers. Such devices generally have a honeycomb structure that, if on the one hand is effective in the retention of the grease, on the other hand to enable the delivery of grease, needs to be subjected to the action of the centrifugal force. This feature heavily restricts the use of such devices, being the cartridge able to be assembled only on the bearing rotatable ring.
Document JP 2008 095766 A discloses a wheel bearing constructed as a double-row rolling bearing in which predetermined grease is filled. An annular recessed site is formed on a shoulder portion of an outward member, and a wall member is mounted in the recessed site. The wall member has an annular protruded portion 14a integrally formed on an outer peripheral face and fitted to the recessed site, and a tapered face gradually diameter-expanded from the cross center toward the end and formed on the inner periphery. Thus, the grease filled in the bearing flows along the tapered face to double-row outside rolling surfaces with gravity and centrifugal force due to the rotation of the bearing.